Patients in a critical care setting are often vulnerable to a significant risk of developing cardiorespiratory instability. Although instability occurs in only a subset of hospitalized patients, it is associated with markedly increased mortality, which therefore makes the identification of those patients likely to become unstable crucial.
Several studies have demonstrated that a patient exhibiting abnormal cardiorespiratory vital signs at any point during hospitalization predicts increased mortality. Early instability typically manifests as subtle changes in multiple vital signs, while more pronounced single parameter abnormalities occur later.
Known methods are available to monitor and acquire non-invasive hemodynamic parameters to identify cardiorespiratory insufficiency in patients to a high degree, however no such mechanism exists to evaluate and/or predict the likelihood of a patient becoming cardiorespiratory unstable.
Several studies of in-hospital cardiac arrest demonstrate that significant physiological instability precedes arrest, but that it is often undetected or it is detected and not recognized as being serious. Early warning scores and modified early warning scores that calculate a single composite instability score from multiple vital signs have been helpful by providing caregivers with the ability to quantify concerns for instability and support for decisions to intervene or activate medical emergency teams. The compilation of warning scores however, can only define current—albeit more subtle—instability, but cannot predict who is likely to become unstable. As such, a need exists for improving clinical practice by recognizing patients at greater risk of developing cardiorespiratory insufficiency.